Enhancement of oleic acid and vitamin E concentrations of bovine milk using dietary supplements of whole rapeseed and vitamin E

With the aim of reducing the degree of saturation and increasing the C18:1 cis fatty acid content of milk fat, the effects of feeding high levels of whole cracked rapeseed to dairy cows was investigated together with the effect of increasing dietary intake of vitamin E on the vitamin E content of milk. Using a 3 x 3 factorial design, 90 Holstein dairy cows were fed one of three levels of whole cracked rapeseed (0 (ZR), 134 (MR) and 270 g . kg(-1) diet dry matter (DM) (HR)) in combination with one of three intakes of supplementary vitamin E (0 (ZE), 2 (ME) and 4 g . cow(-1) . d(-1) (HE)). Supplementing with up to almost 2 kg . d(-1) of rapeseed oil (diet HR) significantly (P < 0.001) increased C18: 1cis in milk fat, from 181 (ZR) to over 400 g &BULL; kg(-1) (HR) of total milk fatty acids. Concentrations of C18: 0, C18: 2 and C18: 3 fatty acids were also increased ( P < 0.001) but by a much lesser degree, and the saturated fatty acids C4: 0 to C16: 0 decreased substantially. Vitamin E supplementation increased ( P < 0.01) milk vitamin E concentrations from 1.29 (ZE) to 1.68 mg &BULL; kg(-1) whole milk (HE). Thus substantial changes in milk fat composition with potentially beneficial effects on human health were achieved and without any adverse effects on milk taste. However, these improvements must be offset against the substantial reductions ( P < 0.001) observed in voluntary feed DM consumption (ZR, 20.6; HR, 15.2 kg DM . d(-1)), milk yield (ZR, 22.9; HR, 13.2 kg . d(-1)) and milk fat concentration (ZR, 42.1; HR, 33.4 g . kg(-1)) which would not be commercially sustainable unless a considerable premium was paid for this modified milk. It seems likely that the optimum dose of dietary rapeseed is lower than used in this study.

Effect of variety, nitrogen fertiliser and various agronomic factors on the nutritive value of husked and naked oats grain

The effect of variety, agronomic and environmental factors on the chemical composition and energy value for ruminants and non-ruminants of husked and naked oats grain was studied. Winter oats were grown as experimental plots in each of 2 years on three sites in England. At each site two conventional husked oat cultivars (Gerald and Image) and two naked cultivars (Kynon and Pendragon) were grown. At each site, crops were sown on two dates and all crops were grown with the application of either zero or optimum fertiliser nitrogen. Variety and factors contained within the site + year effect had the greatest influence on the chemical composition and nutritive value of oats, followed by nitrogen ferfiliser treatment. For example, compared with zero nitrogen, the optimum nitrogen fertiliser treatment resulted in a consistent and significant (P < 0.001) increase in crude protein for all varieties at all sites from an average of 95 to 118 g kg(-1) DM, increased the potassium concentration in all varieties from an average of 4.9 to 5.1 g kg(-1) DM (P < 0.01) and reduced total lipid by a small but significant (P < 0.001) amount. Optimum nitrogen increased (P < 0.001) the NDF concentration in the two husked varieties and in the naked variety Pendragon. Naked cultivars were lower in fibre, had considerably higher energy, total lipid, linoleic acid, protein, starch and essential amino acids than the husked cultivars. Thus nutritionists need to be selective in their choice of naked or husked oat depending on the intended dietary use. (C) 2004 Elsevier B.V. All rights reserved.

Foods derived from animals: the impact of animal nutrition on their nutritive value and ability to sustain long-term health

Foods derived from domestic animals are a significant source of nutrients in the UK diet. However, certain aspects of some animal-derived foods, notably levels of saturated fatty acids, have given rise to concerns that these foods may contribute to the risk of cardiovascular disease, the metabolic syndrome and other conditions. However, the composition of the many animal-derived foods is not constant and can often be enhanced by manipulating the nutrition of the animal. This paper reviews these possibilities with particular attention to lipids, and draws attention to the fact that milk in particular, contains a number of compounds which may, for example, exert anti-carcinogenic effects. It is clear that the role of animal nutrition in creating foods closer to the optimum composition for long-term human health will not only be more relevant in the future, but will be vital in attempts to improve the health of the human population.

Duration from vine emergence to flowering suggests a long-day or rate of change of photoperiod response in white yam (Dioscorea rotundata Poir.)

The objective of this study was to quantify the effect of photoperiod on the duration from vine (shoot) emergence to flowering in white or Guinea yam (Dioscorea rotundata). The duration from vine emergence to flowering in two clonal varieties of yam (TDr 131 and TDr 99-9) was recorded at 10 different sowing dates/locations in Nigeria. Durations to flowering varied from 40 to > 88 days. Mean daily temperature and photoperiod between vine emergence and flowering varied from 25 to 27 degrees C and 13.1 to 13.4 h day(-1), respectively. Both clones had similar responses to temperature, with base and optimum temperatures of 12 and 25-27 degrees C, respectively. Thermal durations to flowering were strongly related (r(2) > 0.75-0.83) to absolute photoperiod (h) at vine emergence as well as to rate of change of photoperiod (s day(-1)) at vine emergence. The response to absolute photoperiod suggests that white yams are quantitative LDPs, flowering sooner in long than short days. Yams also flowered earlier when the rate of change of photoperiod was positive but small, or was negative. It is suggested that yams may use a combination of photoperiod and rate of change in order to fine tune flowering time. (c) 2006 Elsevier B.V. All rights reserved.